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Autonomic and cardiovascular responses to chemoreflex stress in apnoea divers.
MedLine Citation:
PMID:  20627720     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
Sleep apnoea, with repeated periods of hypoxia, results in cardiovascular morbidity and concomitant autonomic dysregulation. Trained apnoea divers also perform prolonged apnoeas accompanied by large lung volumes, large reductions in cardiac output and severe hypoxia and hypercapnia. We tested the hypothesis that apnoea training would be associated with decreased cardiovagal and sympathetic baroreflex gains and reduced respiratory modulation of muscle sympathetic nerve activity (MSNA; microneurography). Six trained divers and six controls were studied at rest and during asphyxic rebreathing. Despite an elevated resting heart rate (70+/-14 vs. 56+/-10 bpm; p=0.038), divers had a similar cardiovagal baroreflex gain (-1.22+/-0.47 beats/mmHg) as controls (-1.29+/-0.61; NS). Similarly, though MSNA burst frequency was slightly higher in divers at rest (16+/-4 bursts/min vs. 10+/-5 bursts/min, p=0.03) there was no difference in baseline burst incidence, sympathetic baroreflex gain (-3.8+/-2.1%/mmHg vs. -4.7+/-1.7%/mmHg) or respiratory modulation of MSNA between groups. Resting total peripheral resistance (11.9+/-2.6 vs. 12.3+/-2.2 mmHg/L/min) and pulse wave velocity (5.82+/-0.55 vs. 6.10+/-0.51 m/s) also were similar between divers and controls, respectively. Further, the sympathetic response to asphyxic rebreathing was not different between controls and divers (-1.70+/-1.07 vs. -1.74+/-0.84 a.u./% desaturation). Thus, these data suggest that, unlike patients with sleep apnoea, apnoea training in otherwise healthy individuals does not produce detectable autonomic dysregulation or maladaption.
Authors:
Craig D Steinback; Toni Breskovic; Ivana Banic; Zeljko Dujic; J Kevin Shoemaker
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Autonomic neuroscience : basic & clinical     Volume:  156     ISSN:  1872-7484     ISO Abbreviation:  Auton Neurosci     Publication Date:  2010 Aug 
Date Detail:
Created Date:  2010-08-02     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100909359     Medline TA:  Auton Neurosci     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  138-43     Citation Subset:  IM    
Copyright Information:
Copyright 2010 Elsevier B.V. All rights reserved.
Affiliation:
Neurovascular Research Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada.
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